unit MemLibrary;

interface

uses
Windows;


function memLoadLibrary(pLib: Pointer): DWord;
function memGetProcAddress(dwLibHandle: DWord; pFunctionName: PChar): Pointer; stdcall;
function memFreeLibrary(dwHandle: DWord): Boolean;


implementation

procedure ChangeReloc(baseorgp, basedllp, relocp: pointer; size: cardinal);
type
    TRelocblock = record
        vaddress: integer;
        size: integer;
    end;
    PRelocblock = ^TRelocblock;
var
    myreloc: PRelocblock;
    reloccount: integer;
    startp: ^word;
    i: cardinal;
    p: ^cardinal;
    dif: cardinal;
begin
    myreloc := relocp;
    dif := cardinal(basedllp)-cardinal(baseorgp);
    startp := pointer(cardinal(relocp)+8);
    while myreloc^.vaddress <> 0 do
    begin
      reloccount := (myreloc^.size-8) div sizeof(word);
      for i := 0 to reloccount-1 do
      begin
        if (startp^ xor $3000 < $1000) then
        begin
          p := pointer(myreloc^.vaddress+startp^ mod $3000+integer(basedllp));
          p^ := p^+dif;
        end;
        startp := pointer(cardinal(startp)+sizeof(word));
      end;
      myreloc := pointer(startp);
      startp := pointer(cardinal(startp)+8);
    end;
end;
procedure CreateImportTable(dllbasep, importp: pointer); stdcall;
type
    timportblock = record
          Characteristics: cardinal;
          TimeDateStamp: cardinal;
          ForwarderChain: cardinal;
          Name: pchar;
          FirstThunk: pointer;
    end;
    pimportblock = ^timportblock;
var
    myimport: pimportblock;
    thunksread, thunkswrite: ^pointer;
    dllname: pchar;
    dllh: thandle;
    old: cardinal;
begin
    myimport := importp;
    while (myimport^.FirstThunk <> nil) and (myimport^.Name <> nil) do
    begin
      dllname := pointer(integer(dllbasep)+integer(myimport^.name));
      dllh := LoadLibrary(dllname);
      thunksread := pointer(integer(myimport^.FirstThunk)+integer(dllbasep));
      thunkswrite := thunksread;
      if integer(myimport^.TimeDateStamp) = -1 then
        thunksread := pointer(integer(myimport^.Characteristics)+integer(dllbasep));
      while (thunksread^ <> nil) do
      begin
        if VirtualProtect(thunkswrite,4,PAGE_EXECUTE_READWRITE,old) then
        begin
          if (cardinal(thunksread^) and $80000000 <> 0) then
          thunkswrite^ := GetProcAddress(dllh,pchar(cardinal(thunksread^) and $FFFF)) else
          thunkswrite^ := GetProcAddress(dllh,pchar(integer(dllbasep)+integer(thunksread^)+2));
          VirtualProtect(thunkswrite,4,old,old);
        end;
        inc(thunksread,1);
        inc(thunkswrite,1);
      end;
      myimport := pointer(integer(myimport)+sizeof(timportblock));
    end;
end;


function memLoadLibrary(pLib: Pointer): DWord;
var
DllMain    : function (dwHandle, dwReason, dwReserved: DWord): DWord; stdcall;
IDH        : PImageDosHeader;
INH        : PImageNtHeaders;
SEC        : PImageSectionHeader;
dwSecCount : DWord;
dwLen      : DWord;
dwmemsize : DWord;
i          : Integer;
pAll       : Pointer;
begin
Result := 0;

IDH := pLib;
if isBadReadPtr(IDH, SizeOf(TImageDosHeader)) or (IDH^.e_magic <> IMAGE_DOS_SIGNATURE) then
    Exit;

INH := pointer(cardinal(pLib)+cardinal(IDH^._lfanew));
if isBadReadPtr(INH, SizeOf(TImageNtHeaders)) or (INH^.Signature <> IMAGE_NT_SIGNATURE) then
    Exit;

// if (pReserved <> nil) then
//    dwLen := Length(pReserved)+1
// else
    dwLen := 0;

SEC := Pointer(Integer(INH)+SizeOf(TImageNtHeaders));
dwMemSize := INH^.OptionalHeader.SizeOfImage;
if (dwMemSize = 0) then Exit;

pAll := VirtualAlloc(nil,dwMemSize+dwLen,MEM_COMMIT or MEM_RESERVE,PAGE_EXECUTE_READWRITE);
if (pAll = nil) then Exit;

dwSecCount := INH^.FileHeader.NumberOfSections;
CopyMemory(pAll,IDH,DWord(SEC)-DWord(IDH)+dwSecCount*SizeOf(TImageSectionHeader));
// CopyMemory(Pointer(DWord(pAll) + dwMemSize),pReserved,dwLen-1);
CopyMemory(Pointer(DWord(pAll) + dwMemSize),nil,dwLen-1);
for i := 0 to dwSecCount-1 do
begin
    CopyMemory(Pointer(DWord(pAll)+SEC^.VirtualAddress),
          Pointer(DWord(pLib)+DWord(SEC^.PointerToRawData)),
          SEC^.SizeOfRawData);
    SEC := Pointer(Integer(SEC)+SizeOf(TImageSectionHeader));
end;

if (INH^.OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC].VirtualAddress <> 0) then
    ChangeReloc(Pointer(INH^.OptionalHeader.ImageBase),
          pAll,
          Pointer(DWord(pAll)+INH^.OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC].VirtualAddress),
          INH^.OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC].Size);
CreateImportTable(pAll, Pointer(DWord(pAll)+INH^.OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress));

@DllMain := Pointer(INH^.OptionalHeader.AddressOfEntryPoint+DWord(pAll));
// if (INH^.OptionalHeader.AddressOfEntryPoint <> 0) and (bDllMain) then
if INH^.OptionalHeader.AddressOfEntryPoint <> 0 then
begin
    try
//      if (pReserved <> nil) then
//        DllMain(DWord(pAll),DLL_PROCESS_ATTACH,DWord(pAll)+dwMemSize)
//      else
        DllMain(DWord(pAll),DLL_PROCESS_ATTACH,0);
    except
    end;
end;
Result := DWord(pAll);
end;


function memFreeLibrary(dwHandle: DWord): Boolean;
var
IDH: PImageDosHeader;
INH: PImageNTHeaders;
begin
Result := false;
if (dwHandle = 0) then
    Exit;

IDH := Pointer(dwHandle);
if (IDH^.e_magic <> IMAGE_DOS_SIGNATURE) then
    Exit;

INH := Pointer(DWord(IDH^._lfanew)+DWord(IDH));
if (INH^.Signature <> IMAGE_NT_SIGNATURE) then
    Exit;

if VirtualFree(Pointer(dwHandle),INH^.OptionalHeader.SizeOfImage,MEM_DECOMMIT) then
    Result := True;
end;


function memGetProcAddress(dwLibHandle: DWord; pFunctionName: PChar): Pointer; stdcall;
var
NtHeader          : PImageNtHeaders;
DosHeader          : PImageDosHeader;
DataDirectory      : PImageDataDirectory;
ExportDirectory    : PImageExportDirectory;
i          : Integer;
iExportOrdinal     : Integer;
ExportName         : String;
dwPosDot          : DWord;
dwNewmodule        : DWord;
pFirstExportName   : Pointer;
pFirstExportAddress: Pointer;
pFirstExportOrdinal: Pointer;
pExportAddr        : PDWord;
pExportNameNow     : PDWord;
pExportOrdinalNow : PWord;
begin
Result := nil;
if pFunctionName = nil then Exit;

DosHeader := Pointer(dwLibHandle);
if isBadReadPtr(DosHeader,sizeof(TImageDosHeader)) or (DosHeader^.e_magic <> IMAGE_DOS_SIGNATURE) then
    Exit; {Wrong PE (DOS) Header}

NtHeader := Pointer(DWord(DosHeader^._lfanew)+DWord(DosHeader));
if isBadReadPtr(NtHeader, sizeof(TImageNTHeaders)) or (NtHeader^.Signature <> IMAGE_NT_SIGNATURE) then
    Exit; {Wrong PW (NT) Header}

DataDirectory := @NtHeader^.OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT];
if (DataDirectory = nil) or (DataDirectory^.VirtualAddress = 0) then
    Exit; {Library has no exporttable}

ExportDirectory := Pointer(DWord(DosHeader) + DWord(DataDirectory^.VirtualAddress));
if isBadReadPtr(ExportDirectory,SizeOf(TImageExportDirectory)) then
    Exit;

pFirstExportName := Pointer(DWord(ExportDirectory^.AddressOfNames)+DWord(DosHeader));
pFirstExportOrdinal := Pointer(DWord(ExportDirectory^.AddressOfNameOrdinals)+DWord(DosHeader));
pFirstExportAddress := Pointer(DWord(ExportDirectory^.AddressOfFunctions)+DWord(DosHeader));

if (integer(pFunctionName) > $FFFF) then {is FunctionName a PChar?}
begin
    iExportOrdinal := -1;          {if we dont find the correct ExportOrdinal}
    for i := 0 to ExportDirectory^.NumberOfNames-1 do {for each export do}
    begin
      pExportNameNow := Pointer(Integer(pFirstExportName)+SizeOf(Pointer)*i);
      if (not isBadReadPtr(pExportNameNow,SizeOf(DWord))) then
      begin
        ExportName := PChar(pExportNameNow^+ DWord(DosHeader));
        if (ExportName = pFunctionName) then {is it the export we search? Calculate the ordinal.}
        begin
          pExportOrdinalNow := Pointer(Integer(pFirstExportOrdinal)+SizeOf(Word)*i);
          if (not isBadReadPtr(pExportOrdinalNow,SizeOf(Word))) then
          iExportOrdinal := pExportOrdinalNow^;
        end;
      end;
    end;
end else{no PChar, calculate the ordinal directly}
    iExportOrdinal := DWord(pFunctionName)-DWord(ExportDirectory^.Base);

if (iExportOrdinal < 0) or (iExportOrdinal > Integer(ExportDirectory^.NumberOfFunctions)) then
    Exit; {havent found the ordinal}

pExportAddr := Pointer(iExportOrdinal*4+Integer(pFirstExportAddress));
if (isBadReadPtr(pExportAddr,SizeOf(DWord))) then
    Exit;

{Is the Export outside the ExportSection? If not its NT spezific forwared function}
if (pExportAddr^ < DWord(DataDirectory^.VirtualAddress)) or
     (pExportAddr^ > DWord(DataDirectory^.VirtualAddress+DataDirectory^.Size)) then
begin
    if (pExportAddr^ <> 0) then {calculate export address}
      Result := Pointer(pExportAddr^+DWord(DosHeader));
end
else
begin {forwarded function (like kernel32.EnterCriticalSection -> NTDLL.RtlEnterCriticalSection)}
    ExportName := PChar(dwLibHandle+pExportAddr^);
    dwPosDot := Pos('.',ExportName);
    if (dwPosDot > 0) then
    begin
      dwNewModule := GetModuleHandle(PChar(Copy(ExportName,1,dwPosDot-1)));
      if (dwNewModule = 0) then
        dwNewModule := LoadLibrary(PChar(Copy(ExportName,1,dwPosDot-1)));
      if (dwNewModule <> 0) then
        result := GetProcAddressX(dwNewModule,PChar(Copy(ExportName,dwPosDot+1,Length(ExportName))));
    end;
end;
end;

end.